Injectable microparticles with nanoparticle-anchored "Solid-like" slippery coating for durable anti-biofouling and enhanced dispersibility.

Injectable microparticles have great potential in tissue engineering and drug delivery. However, their clinical application is limited by the problem of biological contamination, and the inherent contradiction between anti-biofouling efficacy and colloid stability. Traditional strategies (such as drug release coatings and anti-biofouling polymer layers) have defects such as drug exhaustion, poor mechanical stability, and uneven surface coating. Herein, a design paradigm of nanoparticle-anchored "solid-like" slippery coating (SSCMP) was developed by constructing a composite interface layer with both topological structure and chemical anchoring functions on the surface of injectable microparticles, resolving the contradiction between anti-contamination and dispersibility. Specifically, an amide covalent coupling-surface limited self-assembly strategy was adopted to uniformly load amino-functionalized nanoparticles onto the surface of carboxylated microparticles. The nanoparticles exert a dual function: On the one hand, they form surface nano-protrusions, reducing direct particle contact and providing long-term monodispersity in the physiological environment. On the other hand, as lubrication anchor points, it captures silicone oil through electrostatic interaction and firmly locks the lubricants onto the surface of the microparticle through covalent grafting with epoxy resin, forming a stable "solid-like" slippery interface. The collaborative design endows the microparticles with persistent protein repulsion ability both in vitro and in vivo, broad-spectrum anti-biofouling performance against bacteria, significant cell adhesion inhibition effect. And it alleviates the inflammatory response caused by implantation, demonstrating excellent biocompatibility. This strategy breaks through the stability bottleneck of traditional coatings on curved substrates, providing a universal platform for the development of injectable biomaterials with controllable preparation, long-term anti-contamination, and great dispersibility.